Tyre Size Calculator

A tyre size calculator compares overall diameter, sidewall height, and revolutions per kilometre between two sizes — essential before changing rim diameter or section width.

What to compare

Overall diameter affects speedometer, clearance, and gearing. A +1 inch wheel with a lower profile should land near the OEM rolling circumference.

Speedometer error

If the new tyre is taller, you travel faster than the speedo shows. Shorter tyres exaggerate the opposite. GPS can verify real speed after a change.

Load capacity

Calculator maths does not replace load index checks — a flashy wide tyre might still be under-rated for your ute.